What can be done in this situation

Situation : I am in truoble of litigation create by land grabber. Is typed on 100 rs. satmp paper, notory registered taba sathekhat vallied? purchaser not mention time limit to exicute sathekhat.what is time limite for such transactions? He transfer light bill on his name before registered sale deed. He purchase 100 rs stamp on salers name. he is not exicuting further purchase process from 10 years. what can be done to get freedom from forged aggrement to sale? please Guide